Lift racks commonly include a carriage supported between two parallel track members on which the wheels of a vehicle are adapted to be supported. One or more jacks may be carried by the carriage which is mounted to the tracks by trolley assemblies which ride on track mounted rails to permit longitudinal movement of the carriage to the desired position beneath the vehicle located on the tracks.
In order to prevent the carriage from moving after the associated jack or jacks have been operated to support a part of the vehicle, brake means are incorporated into the trolley assembly. The brake means may incorporate braking surfaces which move downwardly against the trolley rails under the weight of the part of the vehicle supported by the carriage. The trolley wheels may be mounted to the carriage by means of elastomeric mounts which bend under the weight of the vehicle to permit the trolley wheels to retract so that the braking surfaces may descend into abutting relationship with the rails.